336 VEGETABLE SUBSTANCES. 



before they venture to gather the mushroom for con- 

 sumption. In judging of the qualities of a mushroom, 

 the smell is not a perfect or safe criterion. If the 

 smell be nauseous, that is a good ground of rejection; 

 but the opposite odour is no decided proof of innoxious 

 qualities. 



In other countries many species of fungi are not 

 only considered edible, but are likewise made the 

 objects of cultivation. A species of boletus is raised 

 by the Italians, for which purpose two kinds of 

 stones are used. The one of calcareous formation, 

 containing vegetable fibre, and found in the chalk- 

 hills near Naples ; the other an indurated turf, from 

 the volcanic mountains near Florence. Both of 

 these have the quality of imbibing moisture, and if 

 either of them be kept in a cellar and constantly 

 watered, it will produce this fungus ; but the water 

 with which they are moistened must occasionally be 

 that in which the boletus has been washed, and in 

 which, of course, its seeds are contained. This 

 proves that, under particular circumstances, some 

 fungi have the power of elaborating their own sub- 

 stance out of moisture and the atmosphere.* At 

 Brescia one species of fungus, Amanila incarnata, is 

 produced from the bruised fragments of the mush- 

 room The Jlgaricus oslreuttts, another edible 

 species, is obtained from the husks of the berries of 

 the sweet bay, Laurus nobilis ; after the oil has been 

 extracted by boiling, the husks are buried in a 

 trench, and are then submitted to considerable pres- 

 sure, and covered with a layer of earth about half a 

 foot thick, and the whole is protected from excessive 

 rain. From this trench mushrooms will spring up 

 in October, and afford a supply during that and 

 the two following months, for three successive years. 

 At Genoa mushrooms are produced in a similar 



* See Transactions of the Swedish Academy, for 1797. 



